I picked the Hammer editor back up. I learned a lot in a few short days, but this map is still only about half-complete. It's going to be a Sandbox map based on Egg Reverie Zone from Sonic Mania. I've still got to finish detailing the map, add 2D sprites to replicate that 2D style in 3D, and a few other things. Whether I finish it and upload it to the workshop or not, remains to be seen.
Sonic Mania artwork for an upcoming YouTube video. Not sure whether I'll be using the top art or bottom art yet. (The bottom one is better as art, but in the context of the Sonic Mania story, people might get confused.)